Aqueous shunt surgery and mitomycin C

Review citation: Foo V, Htoon HM, Welsbie DS, Perera SA. Aqueous shunts with mitomycin C versus aqueous shunts alone for glaucoma. Cochrane Database of Systematic Reviews 2019, Issue 4. Art. No.: CD011875. DOI: 10.1002/14651858.CD011875.pub2

What is the aim of this review?
The aim of this Cochrane review was to compare the effects on intraocular pressure (IOP) between participants who received mitomycin C (MMC) during aqueous shunt surgery and participants who did not receive mitomycin C (MMC) during aqueous shunt surgery.

Key messages
We do not know whether MMC helps to lower IOP after aqueous shunt surgery for glaucoma. All the relevant trials that we found were small and they reported little information on how they were conducted. The difference in IOP between the MMC and no MMC group 12 months after surgery was too uncertain to say whether MMC helped to lower IOP.

What was studied in this review?
Glaucoma is a progressive disease in which the optic nerve is damaged. Damage to the optic nerve results in visual impairment and may result in blindness when not properly treated. Increased pressure within the eye, known as intraocular pressure or IOP, is the only known risk factor for glaucoma that can be treated. It is thought that by lowering IOP, damage to the optic nerve will be reduced in eyes with glaucoma. Treatments to reduce IOP include eye drops, laser surgery (trabeculoplasty), trabeculectomy (surgical removal of part of the trabecular meshwork), and aqueous shunt surgery (a small device is implanted in the eye to help drain fluid to reduce pressure). Aqueous shunt surgery usually is performed in eyes for which eye drops and laser surgery have not reduced IOP.

Sometimes medications, such as MMC, are used alongside aqueous shunt surgery. These types of medications, known as antifibrotic agents, are used to prevent tissue growth around the implanted device which may block the fluid from draining from the eye. However, it is unknown whether these types of medications are effective and whether there are any unwanted adverse effects. The purpose of this review was to evaluate the effectiveness and safety of MMC when used during aqueous shunt surgery.

What are the main results of the review?
We included five studies with a total of 333 eyes with glaucoma. All five trials reported few details about how they were designed and carried out and few outcomes regarding IOP. Thus, we do not know whether MMC was advantageous compared with placebo. We found no clear benefit or harm for MMC versus no MMC during aqueous shunt surgery.

How up-to-date is this review?
Cochrane researchers searched for studies that had been published up to 13 February 2018.